Spectral spell-checker custom function

spell-checker.js

// https://cdn.skypack.dev/nspell
import nspell from 'https://cdn.skypack.dev/pin/nspell@v2.1.5-DeoPrrm6QtcGrVjDyngP/mode=imports,min/optimized/nspell.js';
import { fetch } from '@stoplight/spectral-runtime';
import { createRulesetFunction } from '@stoplight/spectral-core';

function fetchAsset(lang, ext) {
  return fetch(`https://unpkg.com/dictionary-${lang}/index.${ext}`).then(r => r.text());
}

const instances = new Map();

async function createSpellChecker(lang) {
  const instance = instances.get(lang);

  if (instance !== void 0) return instance;

  const [aff, dic] = await Promise.all([fetchAsset(lang, 'aff'), fetchAsset(lang, 'dic')]);

  const spell = nspell({ aff, dic });
  instances.set(lang, spell);
  return spell;
}

function printSuggested(suggested) {
  return suggested.map(JSON.stringify).join(' or ');
}

export default createRulesetFunction(
  {
    input: {
      type: 'string',
    },
    options: {
      type: 'object',
      properties: {
        lang: {
          enum: ['en'],
        },
      },
      required: ['lang'],
      additionalProperties: false,
    },
  },
  async function dictionary(input, opts) {
    try {
      const checker = await createSpellChecker(opts.lang);
      const results = [];

      for (const word of input.split(/\s+/)) {
        const suggested = checker.suggest(word);
        if (suggested.length !== 0) {
          results.push({
            message: `"${word}" is misspelled. Did you mean ${printSuggested(suggested)}?`,
          });
        }
      }

      return results;
    } catch (ex) {
      return [
        {
          message: ex instanceof Error ? ex.message : String(ex),
        },
      ];
    }
  },
);